Multiple antenna for electrical wave transmission



M. I. PUPIN AND E. H. ARMSTRONG. MULTIPLE ANTENNA .FOR ELECTRICAL WAVE TRANSMISSION.

APPLICATION FILED OCT. I, T915- RENEWED JAN. 14,1921.

Patented Aug. 23, 192L ployed in wireless transmissions, tween twentyand one hundred thousand pe- Y [UNITED .STATES PATENT OFFICE.

MICHAEL I. PPIN, or NORFOLK, CONNECTICUT, AND EDWIN n. ARMSTRONG, or f YONxEns, NEW YORK.

MULTIPLE ANTENNA FOR ELECTRICAL WAVE TRANSMISSION.

Specification of Letters Patent.

Patented Aug. 23, 1921.

nlpplieaton filed Uctober 1, 1915, Serial No. 53,494. Renewed January 14, 1921. Serial No. 437,358.

To all 'whom it may concern:

Be it known that we, MrdHAEL I. PUPIN,

a citizen of the UnitedA States, residin in Norfolk, count of Litchfield, State of onnecticut,.andl DWIN H. ARMSTRONG, a citizen of the United States, residing in Yoners, county of Westchester, State of N ew Y ork,have invented certain new and useful Improvements in ultiple4 Antennae 'for Electrical Wave Transmission; and we do hereby declare the following to be a full, clear, and exact description of the invention, such' as will enable others skilled in the art to which it appertains to make and use the same. v The invention relates to the screening of a high resistance wireless receiving antenna against the disturbing effects of electrical impulses of short duration by connecting it to another antenna o f low resistance and low inductano'e. Y i

Figure 1 is a representation of a construction which embodies this invention and rig. 2 shows a modification.

4, 3, 5 is a linear low resistance vertical antenna in which there is no inductance except the uniformly distributed inductance naturally associated with it. Let its height be 500 feet. Its natural period of oscillation will be about 2 X 10'6 seconds, and its damping very hi h, since, as is well known, an antenna of t is construction is avery good radiator. The high resistance antenna 3, 1, 6 is connected at 3 to the low resistance antenna. This high resistance an tenne. is the receiving antenna and yit is sup posed to be tuned to some frequency which is within th`e interval offrequencies now elnthat is beriods per second. On this account it carries large amounts of lumped inductance, as indicated at 7'. This large inductance load in addition to the .high resistance load, which the high resistance4 antenna carries,makes its coupling tothe low resistance antenna very loose, in spite of the 'fact that the linearparts O f the two antennae are as closely coupled to each other as practicable. :When an electrical pulse of short duration strikes the two antenn the low resistance antenna will absorb high and substantially the same as if ther high resistance antenna were not present at all, since the coupling between 'the two is very loose. These high frequency oscillations produce in the'high resistance antenna very little or no effect not only on account of the fact that the high resistance antenna is not tuned to these hi h frequencies, but also on account of the act that'the high frei quency oscillation on the low resistance antenna is 'excessively damped by the well known lradiating power of such antennae:

For simple harmonic waves of the ordinary frequencies now employed# in wireless transmissions, this low resistance antenna is practicallyimpenetrable, so that its connection with the tuned high resistance antenna will not appreciably affect the responsive? ness of this-antenna for waves to which it is tuned.

A very sim le form of cou ling of the two antennae has een described ut 1t is obvious that many variations may be introduced without departing from the essential principles of this invention. For instance, several low resistance antennae running parallel to the high resistance antenna may be employed with considerable advantage. Such an arrangement is shown in Fig. 2 in which a number of low resistance antennae 5 are dis posed about. the high resistance antenna 6 and connected to .the latter and to each other. It will be understood, however, that the low` resistance antennae may be of any number, and may be arranged in any convenient manner with respect to the high resistance antenna.

loo

What We claim is:

A wireless receiving antenna of such high resistance as effeetivelj) to screen the system against disturbing eiectromagnetio Waves 5 impressed upon the conductor, in inductive relation with a low resistance and low inductance antenna which serves as a screen protecting the high resistance antenna against electromagnetic pulses of short dura-A tion. 10

In testimony' whereof we aix our signatures.

LIICHAEL I. PUPIN. EDWIN 4H. ARMSTRONG. 

